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Yan and coworkers created a distance‐dependent enzymatic cascade on a DNA origami surface. Individual pairs of glucose oxidase (GOx) and HRP were placed at specific positions on the DNA origami with controlled spacing (Figure 1.6c) [37]. The distances between the enzymes were systematically changed from 10 to 65 nm, and their activities were evaluated. Two different distance‐dependent kinetics were observed between the assembled enzyme pairs, and by incorporating the intermediate protein, the activity was enhanced due to the hydration shells.

Stein and coworkers performed a combination of multistep energy transfer in a photonic wire‐like structure using an energy‐transfer cascade [38]. Fluorophores that allow alternative energy‐transfer pathways to proceed, depending on the incorporation of a jumper dye, were arranged on a DNA origami surface (Figure 1.6d). An input dye (ATTO488), two output dyes (red fluorophore ATTO647N and IR fluorophore Alexa 750), and two jumper dyes (ATTO565) were placed onto three helices to minimize fluorophore interactions throughout the DNA molecule. Single‐molecule four‐color FRET by laser excitation was used in this study. As designed, the energy‐transfer pathways from blue to red or blue to IR dyes were successfully controlled at the single‐molecule level by the presence of the jumper dyes, which directed the excited‐state energy from the input dye to the output dyes. These results indicate that DNA origami might serve as a circuit board for photonic devices beyond the diffraction limit and at the molecular scale.

These studies show that molecules and nanoparticles can be selectively incorporated into DNA origami, and the enzymatic cascade reactions and energy transfer pathways were controlled in a distance‐ and position‐dependent manner. These systems are relatively easily constructed by the placement of proteins via a corresponding ligand and hybridization of DNA with functional molecules and nanoparticles onto the addressable DNA origami nanostructures.